Dental restorations or prostheses are often made of ceramic materials because ceramic materials generally provide relatively good physical, aesthetic and biological properties. These restorations are often manufactured by an automated process, which typically includes:                capturing data representing the shape of a patient's teeth, for example by scanning a plaster model of the patient's teeth or alternatively by scanning the actual teeth in the patient's mouth;        designing the shape of a dental restoration precursor based on the captured data using software, such as computer-aided design (CAD) software;        machining the dental restoration precursor to correspond to the designed shape, for example, by an automated Computer Numerical Controlled (CNC) machine; and        optionally finishing the dental restoration precursor by sintering and/or veneering.        
A common method of making dental restorations includes milling a restoration precursor out of a blank of a pre-sintered but still porous ceramic material. The blank is typically formed by compacting an amount of ceramic powder. The blank of compacted powder is usually subsequently pre-sintered to provide it with the required mechanical stability for handling and machining. Once the restoration precursor has been obtained from machining the blank the precursor is typically sintered in the further process of making the final dental restoration. During sintering the precursor typically shrinks, generally proportionally, because the initially porous material reduces in porosity and increases in density. For this reason the restoration precursor may be initially larger, for example about 20 to 30%, than the desired final shape after sintering, to account for shrinkage during the sintering step. To form the final dental restoration the sintered restoration precursor may be veneered or otherwise finished.
It has been found desirable that the material structure of the blank is of a generally uniform density. This is because a non-uniform density or inhomogeneity of the blank material may cause the raw dental restoration to shrink non-uniformly in one or more dimensions during sintering. Thus, the precision of the final dental restoration may be adversely affected, resulting in wasted time and expense for a dentist.
It is generally difficult to compact the ceramic powder to create a blank having a generally uniform or homogeneous material structure. Typically compacting the powder requires the powder particles to move relative to each other. However, thereby friction may hinder the movement of the particles. This may result in the particles to block regionally, and such regions may sink again during further compaction while other regions block, and so on. Therefore the blank may have regionally different densities, or in other words the blank may have to some extent an inhomogeneous material structure.
Isostatic compacting processes are often used to manufacture blanks with a relatively homogeneous inner structure. Isostatic compacting processes typically are based on the use of liquid to apply pressure to the ceramic material generally uniformly from all sides, or isotropically. Typically the isostatic processes are used with cylindrical blanks because the cylindrical shape provides for relatively isotropic compaction, and therefore provides for a relatively homogeneous inner structure of such blanks. However, there have been efforts to find alternative compacting techniques that are less expensive, and/or which can be reliably used for different blank shapes.
It is further still desired to manufacture non-cylindrical blanks with a consistently high degree of homogeneity of the inner material. Also, it is a general desire to provide a relatively inexpensive manufacturing process. Especially for dental purposes there is also demand for a manufacturing process that provides for maintaining a high hygiene level during production.